Conventional magnetic fibers which are affected by magnetic fields have been examined. A technology relating to magnetic fibers which are appropriate for application to magnetic recording media or application to clothing by selecting an appropriate type and added amount of magnetic particles, for example, has been disclosed (see Japanese Unexamined Patent Publication S 57 (1982)-167416 (claims)).
Concretely, fibers to which magnetic particles having a high coercive force are added have been proposed as fibers for magnetic recording media. It is necessary to use magnetic particles in needle form having a high coercive force in these fibers in order to gain magnetic fibers. However, the needle form of the used magnetic particles makes it difficult for the magnetic particles to be closely arranged in the fibers, and therefore, it is difficult to contain a high concentration of magnetic particles in the fibers. In addition, it is essential not to increase the ratio of mixture of the magnetic particles, in order to prevent the gained fibers from becoming optically opaque, because of the application. Therefore, the above proposed fibers cannot contain a high concentration of magnetic particles, and thus, lack responsiveness to magnetic fields.
Fibers to which magnetic particles having a low coercive force are added have been proposed, to give an example of magnetic fibers that are appropriate for the other application, that is, application to clothing. These fibers are used for application to clothing, and therefore, it is necessary to reduce as much as possible the amount of magnetic particles, for example, to no greater than 30 wt %, for the purpose of aesthetics. In addition, as one application, these fibers are used to gain knitted articles which are then tufted and cut so as to gain pile knit articles, and after that, processed in a magnetic field, so as to fabricate artificial fur, and according to this technology, these fibers cannot be applied as fibers for mechanical member requiring high precision in design. Thus, conductivity cannot be provided to the fibers, due to the low concentration in the ultimate amount of magnetic particles.
Furthermore, another technology relating to complex fibers with which a magnetic material is mixed has been proposed (see Japanese Unexamined Patent Publication S59 (1984)-173312 (claims, embodiments)). Such complex fibers have a structure where the cores are made of a first component with which a low concentration of magnetic material is mixed, and the sheaths are made of a second component with which a high concentration of magnetic material is mixed, where a polymer having, fiber forming properties of which the melting point is lower than that of the first component is used, and it becomes possible to magnetize the complex fibers having this configuration by means of heat treatment. However, these complex fibers are inferior in resistance to heat and rigidity, due to the low melting temperature of the polymer having fiber forming properties in the second component with which a high concentration of magnetic material has been mixed, and in addition, the fiber properties easily deteriorate with age, in such a manner that the magnetic material peels off during the use of these complex fibers, which, as a result, are inferior in durability for use over a long period of time, and cannot be used as fibers for a mechanical member.
Moreover, magnetic fibers where a magnetic substance is dispersed in fibers, and brush rollers for electro-photographic apparatuses using such fibers have been proposed (see Japanese Unexamined Patent Publication H2 (1990)-193176 (claims, embodiments) and Japanese Unexamined Patent Publication H2 (1990)-193180 (claims, embodiments)). The magnetic fibers disclosed in these patent documents are used by controlling the application of toner that is used in electro-photographic apparatuses through magnetization of the magnetic substance that is contained in the fibers. In this proposal, however, no concrete technical guidance is provided in terms of the amount of magnetic substance in the fibers for controlling the toner cleaning process or a development process through the application of toner, and therefore, the magnetizing properties of the magnetic fibers and the like are unclear. In addition, in order to provide conductivity to the fibers, it is necessary to separately use a conductive microscopic powder. Therefore, the manufacture of fibers for brush rollers which satisfy both the magnetic properties and conductivity, or the manufacture of brush rollers which are easy to clean and excellent in developing cannot be achieved in accordance with this proposed technology.
It could therefore be helpful to provide fibers having excellent responsiveness to magnetic fields and excellent conductivity, that is to say, which are excellent in responsiveness to magnetic fields in such a manner that the fibers are strongly magnetized simultaneously with the application of a magnetic field, and the fibers are not magnetized (do not become magnets) after the magnetic field is gone, and the fibers are sensitive enough to respond to magnetic fields, even when the magnetic field is weak, and in addition, are excellent in resistance to heat in the case where the fibers are incorporated in an apparatus, in the durability for use over a long period of time, and in the stability of a specific resistance value against change in the humidity.
In addition, it could also be helpful to provide textiles, knitted articles and cloths, such as non-woven cloths, using such fibers, short fibers, fiber articles, such as clothing, articles such as brush rollers using such fiber articles, and a variety of apparatuses into which such articles are incorporated.
We conducted diligent research to gain fibers having excellent responsiveness to magnetic fields and excellent conductivity, and during that research, found that it is possible to make fibers contain a material having a specific form and properties and additional merits that cannot be achieved in accordance with the prior art can be provided.